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Diamond recovery

In order to check the role that the density of defects plays in the annealing of damaged diamond, we have repeated the above calculations using the same annealing procedure to a ``mildly damaged'' sample obtained by the energetic displacement of just one atom. This bombardment process creates a lower density of defects. After annealing at 3000 K for 20 ps, no change in the number of threefold coordinated atoms nor in their location was found. Furthermore, no graphitic planes were formed. However, after annealing the sample at 4000 K for 20 ps, and then cooling it very slowly to avoid trapping of atoms in local potentials, we obtained a sample which contained only 14 threefold atoms. That is, 70 % of the threefold coordinated atoms created by the bombardment, transformed back to fourfold coordinated atoms. Thus, the large pressure applied by the diamond matrix and the low density of point defects prevent the damaged region to graphitize, and favor the recovery of sp3 bonds when annealing is applied.

David Saada